TITLE: Towards an understanding of microbial ecosystem function in the polar ocean

ABSTRACT:

The ecosystem functions performed by marine bacteria and archaea enable a broad range of marine ecosystem services, including carbon sequestration and biomass production. Directly observing microbial ecosystem functions remains a challenge however, and we often lack a mechanistic understanding of what functions are provided by what microbes and when they are provided. To better determine what potential ecosystem functions exist within a microbial community of known composition I recently developed a new bioinformatics tool, paprica. Here I’ll describe the application of paprica to a five-year seasonal time series of 16S rRNA gene sequence data from our study site along the West Antarctic Peninsula, a dynamic marine ecosystem facing unprecedented climate-driven change. By connecting community taxonomic structure and metabolic potential as determined with paprica, to physiological data collected by flow cytometry, we are able to test our overarching hypothesis that microbial ecosystem function is itself a function of community taxonomy and physiology. A linear model incorporating taxonomy and cell specific DNA quantity (a measure of cell growth) accounted for 72 % of the variance in bacterial production – a key ecosystem parameter describing the amount of carbon taken up by the bacterial community. I’ll place these findings in a broader ecological context and describe our next steps, including the application of these methods to the global ocean and to communities of bacteria associated with individual phytoplankton cells.